The present invention is particularly suited for use with insect electrocution apparatus, and concerns a novel spacing device for spacing a first wire mesh formed of perpendicularly crossed wires from a second wire mesh formed of perpendicularly crossed wires. The present invention also concerns a novel support for mounting the mesh grid of insect electrocution apparatus to a chassis plate.
Insect electrocution apparatus is well-known in which insects are attracted by means of a light source and are killed as they attempt to reach the light source when they short out a high voltage electrical field surrounding the light source. The vast majority of insects are attracted by light in the ultraviolet portion of the color spectrum. Researchers have determined that the most attractive light source to the majority of insects is one which has its peak output at a wavelength of 360 nanometers. This is the near ultraviolet region of the spectrum generally referred to as "black light." Most black light lamps are of the fluorescent type, and use special phosphors to produce the desired wavelength light output. Black light lamps have been used for many years to attract insects for field surveys of insect populations and other studies.
In the known type of insect electrocution apparatus, in order to electrocute the insect a pair of concentric grids is typically placed around the black light source. The insects must pass through the grid pair ot reach the lamp. A high voltage alternating current source is connected across the grid pair (normally 2,000 to 5,000 volts) to establish a high potential electrical field between the grids. The spacing between grids is set to be great enough to prevent an arc breakdown of this field unless some electrically conductive mass enters the field and effectively shortens the air gap sufficiently to cause an arc breakdown. The body of an insect contains fluids which are electrically conductive, and thus the insect "shorts" the field as it passes through the grid, causing an arc breakdown and passing a high electrical discharge through the insect.
It has been found to be very desirable that the spacing between grids be uniform throughout, that the grid clamping have maximum rigidity and that the grid pair be secured so that it is vibration resistant. Further, it is desirable that the grid pair be constructed to enable simple assembly techniques and that the grid pair have maximum open area to allow insect entry, but the grid element conductors must be close enough to provide a "shortable gap."
Typically each of the grid elements comprises a wire mesh formed of perpendicularly crossed wires. It is an object of the present invention to provide a spacing device for providing uniform spacing of a pair of wire meshes.
Another object of the present invention is to provide a spacing device which achieves rigid clamping of the wire mesh elements.
A further object of the present invention is to provide a spacing device formed of an insulating material which enables a pair of wire meshes to be assembled simply and rapidly.
A further object of the present invention is to provide a spacing device that is useful to space the grid pair of insect electrocution apparatus and allows the grids to be offset with respect to each other to reduce the possibility of an insect passing through without shorting the field.
Another object of the present invention is to provide a spacing device that may be secured so that it is vibration resistant to reduce the shipping loss of fasteners.
A further object of the present invention is to provide a grid support for enabling the secure attachment of the grid assembly to the unit chassis in an insect electrocution apparatus.
A still further object of the present invention is to provide a grid support useful in insect electrocution apparatus formed of an insulating material suitable for the voltages used in such apparatus.
A further object of the present invention is to provide a grid support which is simple in construction and easy to manufacture.
Another object of the present invention is to provide a grid support used in insect electrocution apparatus which is simple and easy to install or to remove for servicing.
A still further object of the present invention is to provide a grid support used in insect electrocution apparatus which is vibration resistant to reduce the possibility of shipping damage.
A further object of the present invention is to provide insect electrocution apparatus utilizing a pair of electrically conductive grid elements which are spaced by a number of insulative spacing devices and are coupled to a chassis plate by means of insulative grid supports.
Other objects and advantages of the present invention will become apparent as the description proceeds.